As the fossil-fuel age draws to a close there will remain a substantial need for liquid fuels, so an increasing proportion of energy and products will have to come from biomass. At the same time, due to increased population and current food consumption trends, the world will need to produce 50-70% more food by 2050. Using conventional production techniques, these two paradigm shifts would require the increased use of land space for crops, which may be difficult given other land-use requirements. However, the oceans present a solution through the production of various seaweeds, or macroalgae, that can serve multiple purposes by both feeding humanity and powering civilization. Given the vastness of the oceans and the rapid growth rates of seaweeds, a significant portion of our food and energy needs could be met by farming the oceans.
However, present methods of macroalgae farming are suitable only in shallow waters where multiple, opposing anchors can be economically deployed to provide the structure needed for deploying longlines. Even in shallow water, the conventional practice of supporting individual longlines between two opposing anchors is an inefficient use of materials and of ocean space. These methods become unworkable at water depths deeper than found near shore, meaning that any growth in the sector would be confined to that narrow strip of ocean along the coasts where user conflicts are the highest. Marine macroalgae requires seawater, sunlight, and nutrients. Because of the limited depths to which sunlight can penetrate, most natural seaweed beds occur in shallow water over seabed substrates to which it can successfully attach. Present methods of seaweed farming involve the installation of suitable substrates such as ropes to which early-stage macroalgae can attach or are artificially attached. By placing this substrate at or close to the sea surface, useful growth can occur.
In order to realize profitable and efficient production of macroalgae biomass in the ocean technologies are needed to support their cultivation. The key challenge is to dramatically reduce capital and operating cost of macroalgae cultivation, while significantly increasing the range of deployment by expanding into more exposed, deep-water environments.